The invention relates to air mixing devices for use on air conditioning systems, refrigerator systems, and the like. Large fans suspended from the ceiling and rotating in a horizontal plane are increasingly being used to circulate both warm and cool air. While such fans are effective, they are not satisfactory for many room air conditioner applications. Hoffman U.S. Pat. No. 2,583,374 shows an abstract fan which directs air flow at a divider which forces the air back around a fan blade where it is caused to induce additional air flow. Such apparatus is not concerned with mixing air within a room, but, with directing air outside a building.
Presently, existing systems usually utilize primary air handling units or fans where conditioned air enters the space at various supply points. The supply air then mixes the room air. The fan static pressure of the supply fan is usually high to overcome the pressure drop of air conditioning components, such as louvers, filters, ductwork, coils, heat exchangers and air outlets. Since the primary air is sized mainly to handle the heating and cooling needs and to overcome the above described pressure drops, a relatively low amount of air is actually put into motion.
The current methods of air distribution for refrigeration in agricultural and food processing applications result in poor temperature and environmental control. The humidity, air temperature and air motion are uneven and, thus, the results are unsatisfactory. The poor environment in processing food products can cause waste, reduced quality and increased costs as well as health and sanitation problems. The present use of propeller fans to aid in mixing the air helps but fails to provide uniform air distribution. High velocity jet streams still persist. In essence, air conditioning systems for human environments are being used in food processing application with poor results.
Existing systems rely on extensive ductwork and fans to help with air mixing and distribution. In many instances, they are acceptable for human comfort. However, these systems all fail to provide thorough air mixing throughout the room without imposing high air velocity jet streams. These jet streams cause numerous drying problems in the meat processing industry where drying is of the utmost importance. The air film thickness surrounding the product varies greatly with all existing systems. The vapor pressure differential is controlled by air film thickness from velocity, temperature and humidity. The food products are usually stacked close together, and existing systems result in non-uniform drying. Case hardening, spoilage, waste, poor quality, long drying time and high production costs are common.
The advantage of the present invention is that it converts all the fan energy to inducing the mixing of air by aspiration from low air pressure areas created by high velocity. The present invention may be used with almost any existing environmental system to radically improve the quality of the environmental control. This is achieved mainly by providing more uniform velocity and eliminating large temperature differentials (hot and cold spots and drafts), providing uniform humidity thereby causing the temperature control system to function more precisely. In the agricultural and food processing industries, the invention can provide the high quality environment needed to produce uniform finished products.
One particularly advantageous application of the present invention is in the area of meat processing, such as the processing of salami and pepperoni. These products are stored in large drying or aging rooms for 15 to 30 days to properly cure. They are dried slowly by a combination of factors including air velocity, temperature and humidity, product composition, weight, diameter, etc. The most critical factor is the air velocity that flows over the product. This regulates the air film thickness surrounding the product and maintains the moisture vapor pressure differential between the product and the room air. The accurate control of this air film thickness can be provided with this invention. The overall air motion in the room is increased many times over all conventional methods with no increase in energy and without high velocity air jet streams. Air motion is provided around all products and is uniform through the room. All products are cured at the same rate, resulting in high quality products. The speed of drying is also increased, thereby reducing processing costs. This is done by reducing the air film thickness on the surface of the product uniformly throughout the room.
An existing environmental system, which would otherwise have to be replaced to provide satisfactory operation, often will be satisfactory when used with the air inducing device in accordance with the invention. The modifications to conventional systems are generally inexpensive and minor, since the air inducing device of the present invention may be easily added. It is difficult to oversize or undersize any such devices. The larger the air mixing system added, the better the entire system works (within reasonable limits).
In addition to the relatively low cost of modifying the existing air conditioning system, many other benefits are realized. Drying time for processed meats is reduced, mold and mildew are eliminated on interior space surfaces, production time is speeded up, product quality is improved, waste is eliminated, and less energy is consumed. All these are benefits to the consumer. Another benefit is that a small fan can effectively put in motion many times its primary air output due to the configuration of the device. Not only will a great quantity of air be put into motion, but all high velocity air streams will be substantially reduced.
This invention is the only high air volume, low velocity, low energy use air mixing device that does not use ductwork.
It works on the laws of "conservation of momentum" wherein the high velocity mass of primary air from the fan is redirected at the air induction blades. Room air is induced into this high velocity air. The result is a great mass of mixed air set in motion at low velocity.
The blades of the device could be made adjustable to obtain the ideal mixing rate for rooms of differing size, shape and height.
An object of this invention is to provide a simple, inexpensive, effective means of supplying uniform temperature, humidity and air movement within a given space. This air inducing device thoroughly mixes all the air in the room, creating a homogeneous mixture without any high velocity air streams. This device will be especially useful in the agricultural and food processing industries. Use of this device will result in uniform processing of food products, thereby minimizing food product waste, lowering product cost and improving its quality.
A further object of this invention is to correct the numerous environmental problems that currently exist both for industry and food processors.